Tuesday, 21 October 2014

Memetic sex

Memes like genes clearly recombine. It is a simple matter to point to what were once independent memes fused together. Portmanteaus are an obvious example. For example:

"Sheeple" - a portmanteau of sheep and people;

"Spork" - a portmanteau of spoon and fork;

It is fairly common to use the term "sex" as a synonym for "recombination". For example, this is what Matt Ridley seems to do - when he says that ideas have sex.

However, not everyone shares this broad conception of sex. For one thing, you can recombine your own genes with each other - for example as an error-correction strategy, but - unless the process involves outcrossing - few would classify this as being sex. Another issue is pathogens. A retrovirus that infects your cells is certainly recombining its genes with yours - yet many people would be reluctant to call refer to this form of recombination as being "sex".

This leads to the question of how best to distinguish between sex and disease. One apparent difference is that sex involves members of the same species - whereas disease involves members of different species. However the most common definition of what a species is invokes the idea of sexual reproduction. To simultaneously define "species" in terms of "sex" and "sex" in terms of "species" would be circular.

Other differences might be invoked: parasites have shorter generation times, smaller bodies and smaller genomes than their hosts. However, most of these differences apply to genuine males somewhere or another in biology. They seem unsuitable to act as a basis for classification.

My view is that the best way to distinguish sex from disease is to see whether the recipient benefits from its injection of genes. If it willingly accepts the genetic donation, that's sex. If it rejects them - or tries to - that's disease. This raises some corner cases - such as cases of rape. These cases suggest a slightly different criterion - it's sex if there are adaptations favouring the incorporation of the injected genes - and it's disease if adaptations resist them.

I wrote up this idea in 2007 - in an essay titled: "Sex is not a disease" - and I think the idea has stood up well to the test of time.

Having said what we mean by sex, it is now possible to address the issue of sex in cultural evolution. The portmanteaus we originally gave as examples of recombination don't look much like sex or disease - they are one-off events. However, there are some cases of cultural evolution that seem more sexual:

Fashion products - Fashion generates enormous cultural diversity. If you just think about shoes, the number of varieties on sale at any time is enormous - and cultural sexual recombiantion seems like a tempting explanation. Here, recombination is ritualised into annual fashion shows - where the designers go to copy each other's products.

Printer-cartridge diversity - in my 2011 memetics book I gave printer-cartridge diversity as an example of parasite driven recombination. The parasites in this case are the cartridge-cloning companies. Parasites drive a lot of sexual recombination in the organic realm - and it looks as though similar diversity is produced in cultural evolution in response to parasitism.

Experimentation on consumers - some internet companies (such as Google) run regular experiments on their users. They change the colours scheme, the positioning of adverts - and so on. At any time people may be participating in many different experiments - and multiple experiments are run simultaneously - to gather data about their interactions. The dynamics here involve a kind of ritualized recombination.

Genetic algorithms and memetic algorithms - anyone who denies the existence of cultural sex surely faces a strong challenge in explaining how these optimisation techniques work without invoking the concept of cultural sex.

Even with the relatively strict definition of "sex" given here, it seems as though cultural evolution exhibits sexual recombination. I am not really clear on what Richard Dawkins meant in 2005 - when he said (of memes):

One respect in which they are not like genes is that there is nothing obviously corresponding to chromosomes or loci or alleles or sexual recombination.

Memes do have sexual recombination. I don't think there is room for much argument about that. If your conception of sex doesn't apply to cultural evolution, you probably don't have a very useful conception of it.

Sex has been described as being "nature's masterpiece". It is true that there are quite a lot of monocultures in cultural evolution. Many products for example, occur in many identical copies. Microsoft's Windows is a monoculture. However like many monocultures it has been plagued by pathogens.

However, nonetheless, there is sex in cultural evolution. Even a fairly cursory look at the fashion world shows the impact of regular sexual recombination on product diversity.

In the organic realm, sex often leads to gamete size dimorphism. It is possible to see this in companies - with some large, fat organizations provision resources, while other small, meme-carrying mobile agents of various types flit between them. There's also an equivalent of female choice. Interviews, testing by R+D departments, and carefully scrutinized fundraising pitches all qualify here.

Sex has proved popular in the organic realm. No doubt it will become similarly popular in cultural evolution. After all, regular recombination with outcrossing is the best way that is known to explore large, complex search spaces.